Shimmy dampener



Sep't. 8,A 1953 w. H. CLARK ET AL 2,651,385

SHIMMY DAMPENER Filed April g3, 1950 eil- ATTORNE Patented Sept. 8, 1953 SHIMMY DAMPENER Warren H. Clark, Glendale, and Thomas H. Mead,

Los Angeles, Calif., assignors to United Products, Inc., Dayton,

Ohio

Aircraft Ohio, a corporation of Application April 18, 1950, Serial No. 156,704

3v Claims.

. draulic flow restriction.

A further object of the invention is to enable easy adjustment of the flow restriction. Still another object is to provide for automatic thermal and leakage compensation in the device.

A still further object is to present a device of the kind described which is readily adaptable to mass production in various sizes and strokes of movement and which is simply maintained and serviced.

Other objects and structural details of the invention will appear from the when read in connection drawing, wherein:

Fig-l is a view in side elevation of an aircraft nose wheel assembly incorporating a shimmy dampener in accordance with the instant invention;

Fig. 2 is a view of the front elevation;

following description with the accompanying shimmy dampener in Fig. Sis a view in vertical longitudinal section, Y

taken substantially along the line 3 3 of Fig. 2, and enlarged with respect thereto; and Fig. 4 is a View in horizontal longitudinal section, taken substantially along the line 4 4 of Fig. 2, and enlarged with respect thereto.

Referring to Fig. 1 of the drawing, a shimmy dampener in accordance with the instant invention is shown, indicated at i9, in one type of installation to which it is adapted. According to this installation, Which deals with anl aircraft nose wheel, a cylinder strut I I is connected to an aircraft body I2 for swinging motion in a longitudinal direction. The strut I I receives a plunger I3 and incorporates suitable means for damping axial thrusts of the plunger. On the outer projecting end of the plunger i3 is mounteda yoke I4 carrying the nose wheel I5. When landing, the strut II and Wheel I5 are heid, in about the position shown, `by a link I6 which is also operative to draw the assembly into a retracted position during-night. The vertical shocks of landing and taxying imposed Aupon the nose Wheel are sustained and absorbed within the strut I I.' Shimmy and castering movements of the Wheel are absorbed lbyaniauxiliary- .shock absorber, such as (o1. iss-8s) the device I0 hereof which, as shown, is made fast to a'bracket 20 onthe strut II. In communicating torque impulses vfrom the wheel to the dampener I0 any suitable linkage may be used, for example, that illustrated wherein links I1 and I8 connect the yoke I4 to a collar I9 vloosely mounted von the strut II. The collar I9 is in turn connected, by means including a link 2l to a shaft 22 projecting from the dampener I0. According to the construction and arrangement of parts a swivelling motion of the nose wheel I5 is transmitted through the described linkage to shaft 22 which tends to rotate in a corresponding direction. i

Considering now the structural details of the shimmy dampener, it comprises, as shown in Figs. 2, 3 and 4, an approximately T shaped body 23 presenting intersecting through bores 24 and 25. The bore 24 is counterbored at one end thereof to denne a chamberA 26 receiving a bushing 21. The base of the bushing 21 is screw threaded into the body 23 and is further keyed thereto by a radial set screw 28.V AThe inner projecting end of the bushing 21 is reduced in diameter and abuts an annular flange 29 on the shaft 22, the flange29 having a toothed formation to act as pinion. The shaft 22 has a rotatable mounting in the bushing 21 and in `a complementary bushing 3I which abuts the opposite side of the ange 29 and seats in the top of chamber 26, with a skirted part of the bushing 3| being received in the bore 24 beyond chamber 26. The shaft projects through and beyond the outer end of the bushing 21 and its end is formed with a threaded surface 32 and a serrated surface 33. 1 The surface 33 is so formed for positive gripping engagement with the motion transmitting linkage while surface 32 is adapted to mount a retainingv nut or the like.

The'interior of the shaft 22 is partly bored out to serve as a reservoir for hydraulic fluid, such reservoir communicating through radial ports 34 in theshaft and registering ports 35 in bushing 3| with the chamber 26. Beyond the open inner end-of the shaft 22 is a piston 36 reciprocably mounted in the bore 24. That end of bore 24v adjacent piston V36- is closed by a removable Wall 31'dening, with the piston 36, a pressure chamber 38. A valve 39 is mounted in the wall 31'and provides a means of admitting compressed' air y,to the chamber 38, furnishinga yielding force urging the piston 36 downwardv or inA a direction to exert pressure upon hydraulic fluid contained in thespaces below it. Y

The bore 25 is' oiset from the longitudinal plane of bore 24 but intersects bore 24, communirestricted orifices in said pistons for the escape of hydraulic uid from said pressure chambers, said rack and pinion connection comprising a rack formed on said piston rod and a pinion formed on said shaft.

WARREN H. CLARK. THOMAS H. MEAD.

References Cited in the le of this patent UNITED STATES PATENTS Number Number Number Name Date Peteler Apr. 3, 1934 Best Aug. 15, 1939 Kops et a1. Jan. 15, 1946 FOREIGN PATENTS Country Date Great Britain Nov. 26, 1931 Great Britain Oct. 13, 1937 

